there are some good articles on the topic elsewhere on thier site (try looking under “white papers” in the developer section).

Good luck

P.S. OK, after posting, it just occurred to me that you might be talking about static lightmapping/shadowmapping. If thats the case, sorry. I guess I’ve just been really caught up in dynamic lighting and shadowing lately and I kinda forgot there was anything else

The basic idea behind a shadow map is to render the scene from the perspective of the light source into a buffer not unlike a z-buffer. Now each pixel in the buffer stores the distance to the light source. This buffer is called a shadow map.

Then you render the scene from the camera using only ambient lighting. The values in the shadow map are compared with the z-buffer values. This means you do not need to render lighting, texturing or color values in this pass. Some problems occur with this method though: your shadows will appear blocky if your buffer depth is not high enough.